Most conventional carpets comprise a primary backing with yarn tufts in the form of cut or uncut loops extending upwardly from this backing to form a pile surface. Other carpets are needle felt carpets, which are produced by compressing fibers onto textiles or other backing materials and then applying a binding agent so that the fibers are attached to the backing more durably.
Many residential and commercial carpets are also manufactured with a woven scrim (typically made from polypropylene) attached to the back of the carpet to provide dimensional stability to the carpet. These are dual layer products, where two coating layers (precoat for tuft anchorage and adhesive for scrim fixation) are added wet, and the scrim is added afterwards. After optional fixation of the scrim, the carpet is cured at 130 to 200° C. for a certain time.
Where applicable, for both the pre-coat and the adhesive layer, the physical properties of the binder are important to their successful utilization as carpet coatings. In this regard, there are a number of important requirements which must be met by such coatings. The coating must be capable of being applied to the carpet and dried using the processes and equipment conventionally employed in the carpet industry for latex, e.g. emulsion, coating. The binder composition must provide excellent adhesion to the pile fibers to secure them firmly in the backing. Further, coatings used as adhesives must also be able to secure substrates to the carpet secondary backing, thereby enabling the preparation of material for use in wall-to-wall carpeting.
The binders in coating and adhesive compositions for carpet materials are frequently emulsion polymers, i.e., latex dispersions, such as styrene-based emulsion copolymers like styrene-butadiene latex (SBL) materials or such as acrylic polymer latex dispersions. Copolymers of vinyl esters (such as vinyl acetate and vinyl verstate) and vinyl ester/ethylene can also be used and can frequently have cost and performance advantages such as flame retardancy over styrene-based coatings and adhesives such as SBL. For example, vinyl ester copolymers can be used to provide carpet products which are desirably low in VOC (volatile organic compound) content and which do not contain potentially toxic materials such as 4-phenyl cyclohexene (4-PCH) and related compounds which can be found in styrene-butadiene-based polymer dispersions. Vinyl ester copolymers form carpet coating and adhesive layers which are also advantageously resistant to degradation by visible light and/or ultraviolet (UV) radiation.
Carpet coating compositions based on vinyl ester/ethylene, e.g., vinyl acetate/ethylene (VAE), copolymers and also containing a variety of filler materials are disclosed, for example, in U.S. Pat. Nos. 5,026,765; 5,849,389; and 6,359,076. In U.S. Pat. No. 4,735,986, there are disclosed carpet backing adhesive compositions comprising vinyl acetate/ethylene copolymer emulsions and relatively large amounts of fillers. By utilizing VAE copolymer emulsions which have been stabilized with both nonionic surfactants and various forms of hydrolyzed polyvinyl alcohol, the '986 patent carpet adhesive compositions are realized which have acceptable viscosity characteristics and hence desirable compatibility between the VAE copolymer and filler material
Notwithstanding the availability of carpet coating compositions containing both VAE copolymer binding agents and various types of filler materials, it would be advantageous to provide additional VAE-based carpet coating compositions which comprise certain selected types of filler material. Such selected types of filler material would be those like particulate carbon or fly ash materials that can impart odor-controlling and odor-absorbing properties to carpet products having such compositions incorporated therein. And it would be further advantageous to provide carpet coating compositions of this type which have acceptable viscosity characteristics such that they can be effectively supplied and applied to carpet products via conventional commercial scale carpet coating procedures and equipment. By selecting and combining certain types of surfactant- and colloid-stabilized VAE-based copolymer emulsions and certain types of filler materials, such desirable carpet coating compositions and carpet products can be realized as described hereinafter.